An organic light-emitting diode device, also called an OLED device, commonly includes a substrate, an anode, a hole-transporting layer made of an organic compound, an organic luminescent layer with suitable dopants, an organic electron-transporting layer, and a cathode. OLED devices are attractive because of their low driving voltage, high luminance, wide-angle viewing and capability for full-color flat emission displays. Tang et al. described this multilayer OLED device in their U.S. Pat. Nos. 4,769,292 and 4,885,211. OLED devices are generally anticipated to overtake liquid crystal displays (LCDs) as the preferred display technology.
Degradation of the output intensity occurs over time, which can lead to hue shifts or loss of contrast. Many approaches have been attempted to improve the operational stability of OLEDs. In U.S. Pat. No. 6,104,137, Abiko et al. enclosed an oxidizing gas within an airtight case. However, enclosing a gas within an airtight case adds to the complexity of manufacturing an OLED device. Moreover, long term effects of oxygen diffusing into the OLED device can be detrimental to the operating life of the device. There is therefore a need to develop a method to improve the stability of OLED devices using stabilizing dopants without causing a deterioration of the color.